This core, coordinated by Dr. Ambinder, will characterize diagnostic biopsy specimens and evaluate serology. Hodgkin's specimens from patients identified prospectively in Boston or Connecticut or retrospectively through the or through the military bank will be evaluated. Each will be reviewed by Drs. Risa Mann and Michael Borowitz, both nationally recognized hematopathologists. Tissues will be evaluated by conventional light microscopy with hematoxylin and eosin and by immunoperoxidase with a standard panel of antigens including CD15 (LeuM1) and CD3O (Ki1). Biopsies will be classified as Hodgkin's disease or other, and cases of Hodgkin's disease will be subcategorized as lymphocyte predominant, nodular sclerosis, mixed cellularity, lymphocyte depleted, lymphocyte-rich classical Hodgkin's or unclassifiable Hodgkin's. Specimens will be studied by in situ hybridization (for EBER1) and antigen detection by immunohistochemistry (LMP1 and EBNA1). In addition, specimens will be studied to determine expression of various lytic antigens. These histologic studies will ensure the highest standards of diagnostic accuracy with regards to the diagnosis of Hodgkin's disease and its subtyping. Serology specimens collected in the prospective and serum bank study will be evaluated. All of the sera will be titrated in traditional assays on EBV cell lines to detect IgG and IgA antibodies to VCA, EA-D, EA-R, and EBNA. In addition, titers to EBV antigens expressed in cell lines expressing individual EBV genes will be titrated.